There is a progressive rise in d-dimer levels throughout pregnancy, and this remains elevated in the postnatal period. The role of d-dimer testing in pregnancy remains controversial. RCOG guidelines advise not to test d-dimer in pregnancy, as do the American thoracic society guidelines. The European society of cardiology suggest that a negative d-dimer level can be used to rule out PE in pregnancy, however the d-dimer is unlikely to be with normal range.

Pre-test probabilityassessment such as the WELLS score have not been validated for use in pregnancy.

Choice of further imaging will depend upon availability within the hospital.

V/Q scan – ventilation component can often be omitted therefore minimising radiation to the fetus. Main concern is radiation dose to fetus, causing a very small increase in the risk of childhood cancers.

CTPA – more readily available. Can identify other pathology. Increased radiation dose to breast tissue, therefore increasing the risk of breast cancer. Radiation dose to the fetus is less than a V:Q scan.

Women should be counselled on options for further imaging. Factors such as the background risk of breast cancer for that lady, should be taken into account.

Treatment

LMWH – should be commenced immediately, until the diagnosis can be excluded. Dose should be titrated against the womens booking or early pregnancy rate. There have been a number of study’s comparing once daily dosing with BD dosing, with insufficient evidence to favour one option.

Anti-Xa monitoring is not required routinely in pregnancy. Only women at extremes of body weight (<50kg or >90 kg), or with other complicating factors (renal impairment, recurrent VTE).

Routine platelet count monitoring is not required.

Delivery plan – women should be informed not to adminster any further LMWH once in established labour. If delivery is planned, by c-section or induction, LMWH should be discontinued 24 hours prior to planned delivery. Regional anaesthesia should not be undertaken until at least 24 hours after the last dose of LMWH. LMWH should not be given for 4 hours after the use of spinal anaesthesia, or after epidural catheter has been removed. Epidural catheter should not be removed within 12 hours of admistraion of LMWH.

Anticoagulation should be continued for at least 6 weeks postnatally, or until 3 months of anticoagulation has been given in total. Warfarin can be introduce at 5 days postpartum. DOACs can be consider in women who are not breastfeeding.

Massive life threatening PE – consider intravenous unfractionated heparin, thrombolytic therapy, thoracotomy, or surgical embolectomy. If the patient has received thrombolysis (often anticoagulation alone with not reduce the obstruction in the circulation), the loading dose of unfractionated heparin should be omitted and infusion commenced at an hourly rate.

IVC filter may be consider in patients with recurrent PE despite adequate anticoagulation, or in the peripartum period when anticoagulation is contraindicated.

Future pregnancies

Women with previous VTE should be offered thromboprophylaxis throughout the antenatal period. In this case it would be useful to know the patients family history. Thrombophilia testing would only be indicated in patients with a positive family history. The finding of antithrombin deficiency would potentially change management in future pregnancy’s as an intermediate or therapeutic dose would be indicated. However without a significant family history, there would be no indication for further testing as management would not change for this lady as she would qualify for thromboprophylaxis in future pregnancy’s. Technically, a positive family history should have been identified by the midwife at the booking in appointment. Thrombophilia testing should not be undertaken during pregnancy.